Solar Panel Voltage Calculations

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By Edgardo Villalobos

Calculations to find what voltage and current the solar cells need to provide to charge the battery in 8 hours.

Table of Contents

Voltage

Battery 

  • Solar Panels need to be able to charge a 12-Volt, 7-Ah (10-Ah) battery

Rule of thumb 

Rule of thumb: Solar Panel Voltage = Battery Voltage x 1.5

                            Solar Panel Voltage = 12-V x 1.5

                            Solar Panel Voltage = 18-V

  • The Solar Panel needs to charge the battery in 8 hours

Current

Rule of thumb: Amps = Amp Hours / Hours

                             Amps = 7-Ah / 8-hrs            Amps = 10-Ah / 8-hrs

                             Amps = 875-mA                    Amps = 1.25-A